If a coning bolt has failed to maintain tension due to fatigue/embrittlement/over-torquing, or for any other reason, then the immediate outcome is that the disk is not teetering about the teeter hinge, it becomes some point offset in the direction of the coning bolt that has lost tension. That is annoying in the hover.. in forward flight it would impose some pretty dramatic loads.
I think you nailed it .... CF plus the right tension on the coning hinge (frictional pre-load) helps keeps each blade in place so that any flap movement is at the teeter hinge only .... and everything works perfect.
But if one cone hinge has more (or less) freedom of movement than the other .... all of a sudden you have two or three hinge points trying to figure out which one should provide the momentary flap in
some situations.
CF should be the main contender in keeping the cone angles the same on both blades ..... but a split second out-of-phase situation could occur if one cone hinge is sticky or one is too loose .... without a drag hinge an out-of-phase blade will begin to self destruct within two rotations.